1. Field of the Invention
The present invention relates to a horizontal rotary compressor which can be utilized for refrigeration and airconditioning.
2. Discussion of Background
FIG. 20 is an axial sectional view showing the horizontal rotary compressor which is described in Japanese Patent Application No. 85308/1989 and has not been laid open to the public. FIG. 21 is a sectional view taken along the line XXI--XXI of FIG. 20 to show the structure of a lubricating oil pump. Besides the lubricating oil pump shown in FIG. 21, there is for example the lubricating oil pump which has been disclosed in Japanese Examined Utility Model Publication No. 23993/1983 and is shown in FIG. 22.
In FIG. 20, reference numeral 1 designates a sealed shell which houses a compression unit 2 and an electric drive unit 3 side by side in the substantially horizontal (transverse) direction, and in the bottom of which a lubricating oil 4 is accumulated. The compression unit 2 comprises a cylinder 5, a piston 6 which eccentrically rotates in the cylinder 5, a crankshaft 7 which drives the piston 6, a frame 9 having a main bearing 8, a head 11 having an end bearing 10, a vane 12 which functions to divide the inside of the cylinder 5 into a high pressure chamber and a low pressure chamber, and which reciprocates in contact with the piston 6, a lubricating oil pump 13 which provides the crankshaft 7 with the lubricating oil 4 in the bottom of the sealed shell 1 to lubricate sliding parts in the compression unit 2, and a frame side discharge muffler 14 and a head side discharge muffler 15 which are mounted on the frame 9 and the head 11, respectively. The main bearing 8 and the end bearing 10 are used to support the crankshaft 7 and to close both end surfaces of the cylinder 5. The frame side discharge muffler 14 and the head side discharge muffler 15 are provided with projections 16 and 17 which are used to direct a compressed refrigerant gas to locations approximate to the wall of the sealed shell 1, the projections 16 and 17 being made of shut metal parts or tubular parts.
The electric drive unit 3 comprises a stator 18 and an armature 19, at least one of which has passages 20 for passing the refrigerant gas. The compression unit 2 and the electric drive unit 3 are housed so as to be next to each other in the sealed shell 1. In the sealed shell 1, there are formed three spaces, i.e. an A space (electric motor space) defined by the sealed shell 1, the stator 18 and the armature 19, a B space defined by the electric drive unit 3 and the compression unit 2, and a C space (pump space) defined by the compression unit 2 and the sealed shell 1. The projections 16 and 17 communicate with the A space through a bypass pipe 21 which is arranged outside the sealed shell. The C space is provided with a discharge pipe 22 which is used to cause the refrigerant gas to flow out of the sealed shell. As a result, the compressor of FIG. 20 has a refrigerant passage which starts at the discharge mufflers 14 and 15 and ends at the discharge pipe 22 through the bypass pipe 21, the A space, the passages 20 of the electric drive unit, the B space and the C space.
As stated earlier, there are the lubricating oil pumps 13 for horizontal rotary compressors as shown in FIGS. 21 and 22. FIG. 21 is the sectional view taken along the line XXI--XXI of FIG. 20. In FIG. 21, reference numeral 23 designates a lubricating oil feeding tube. Reference numeral 24 designates a refrigerant tube which is fixed to be inserted into the lubricating feeding tube 23. The lubricating oil feeding tube 23 has one end arranged in the lubricating oil 4, and the other end arranged in the substantially central portion of the discharge muffler 15 together with a cup 25 for leading the lubricating oil 4 to the crankshaft 7. The refrigerant tube 24 has one end inserted into the lubricating oil feeding tube 23, and has the other end communicated with the space in the discharge muffler 15.
The other lubricating oil pump that has been used is constituted as shown in FIG. 22. A muffler 26 which has a head and a discharge muffler in one piece is formed with a discharge hole 27 and a lubricating oil pump groove 28. In addition, a cover 29 is bolted to the discharge muffler. The lubricating oil pump is formed in that manner. Reference numeral 30 designates a discharge valve which is mounted at the discharge hole 27, and which can be opened and closed depending on the pressure of a refrigerant gas in a compression chamber 31.
In operation, the electric drive unit 3 is driven to rotate the crankshaft 7. The piston 6 eccentrically rotates in the compression chamber (not shown), and compresses the refrigerant gas with the vane 12 which is in contact with the outer peripheral surface of the piston 6 and is supported by the cylinder 5. The compressed refrigerant gas is discharged from discharge holes 32 and 33 which are formed in the frame 9 and in the head 11, respectively. The refrigerant gas thus discharged spreads in the discharge mufflers 14 and 15. The refrigerant gas which is in the discharge muffler 14 at the side of the frame 9 flows into the bypass pipe 21 through the projection 16, and reaches the A space. On the other hand, the refrigerant gas which has discharged in the discharge muffler 15 at the side of the head 11 partly flows through the refrigerant tube 24 of the lubricating oil pump 13. The lubricating oil is supplied to crankshaft 7 from an oil intake port 34 of the lubricating oil feeding tube 23 by the use of the energy of the refrigerant gas which is flowing at a high speed. The remaining refrigerant gas which does not work for feeding the lubricating oil flows into the bypass pipe 21 through the space in the projection 17 which is mounted to the discharge muffler 15 at the side of the head 11. Then the refrigerant gas passes through the bypass pipe 21, and reaches the A space. The refrigerant gas which has reached the A space arrives at the B space through the passages 20 which are arranged in at least one of the stator 18 and the armature 19. The refrigerant gas passes through a through hole 35 in the cylinder 5 and reaches the C space. After that, it flows out of the sealed shell 1 through the discharge pipe 22 which is arranged in the C space.
In FIG. 20, arrows indicate the flow of the refrigerant gas. In FIG. 21 wherein there is shown the lubricating oil pump for compressors, arrows (.rarw.) in black indicate the flow of the compressed refrigerant gas. Arrows ( ) in white indicate the flow of the lubricating oil. The arrows in black and white indicate the oil feeding operation by the lubricating oil pump.
The flows of the refrigerant gas and the lubricating oil in the lubricating oil pump of FIG. 22 are like those of the oil pump of FIG. 21. The refrigerant gas which has discharged from the discharge hole 27 flows in the oil pump groove 28. When the refrigerant gas passes by an oil intake groove 36 which is arranged below the surface of the lubricating oil (not shown), the refrigerant gas draws the lubricating oil from the oil intake groove 36, and carries the lubricating oil to an opening formed in the end of the crankshaft 7. The difference between the flows of the refrigerant of FIGS. 21 and 22 is follows: In the structure shown in FIG. 21, part of the compressed refrigerant gas is utilized as an oil pump. On the other hand, in the structure shown in FIG. 22, the discharge muffler 26, the head 11, end bearings (not shown), the oil pump groove 28, the oil intake groove 36 and the discharge hole 27 are formed as one piece part, and the compressed refrigerant gas is entirely used as an oil pump.
The horizontal rotary compressors having the structures as stated earlier have the following disadvantages:
1 The projections 16 and 17 which are used to direct the compressed refrigerant gas, the oil pump lubricating oil feeding tube 23 and the oil pump refrigerant tube 24 are made of sheet metal parts or tubular parts, creating problems wherein the necessity of many parts requires a substantial cost, the difficulty in the production takes much time, and there is a strong possibility of getting defectives.
2 The oil pump of FIG. 22 can decrease the number of required parts because the discharge muffler, the head the bearings, the discharge hole, the oil pump groove, the oil intake groove and the like are made as one piece part. However, in order to provide the one piece part with many functions, the number of the machining steps is increased to raise a cost. Because the refrigerant gas has to be entirely used for oil pumping function due to integral structure of the head and the discharge muffler, the proportion of the lubricating oil which is included in the refrigerant gas is increased to deteriorate the efficiency of the compressor and to raise the amount of the lubricating oil which is carried out of the sealed shell. In some operating conditions of the compressor, the refrigerant gas can flow in the oil pump groove 28 in amounts more than needed as an oil pump. As a result, there is a possibility that the refrigerant gas flows off out of the oil intake groove 36, and the oil pump loses its function due to impossibility in oil feeding.